Furnace grate



H. B. HOLT FURNACE GRATE July 21, 1936.

Filed Oct 23, 1934 2 Sheets-Sheet 1 vw aw Fwy/A 4:). AM @m lmm NWITNEzEEs Q H. B. HOLT FURNACE GRATE July 21, 1936.

Filed Oct. 23, 19-34 2 Sheets-Sheet 2 INVENTOR MW; m Mya- MTNESSES a 4.MW

Patented July 21, 1936 ear oFFIeej FURNAGEJ Gem 3 Harriet: H'olt,l'ibr'mbnti Pa; 7' Application flctober 2s, melee-term.masssv iziola ms;(o1 :11 o;4m V

This: inventiont relates e'tofurnace grates; and more. particularly to;traveling; grates of. the end.- lesswchain or beltitypfewhich; by theirmovements; carry: into furnaces new supplies ofi fueltor other 5material. to be burned, andrcarryiiawawthe ashes remainingaftercombustion's. i

Asv chain grates: become heated their' lateral expansion is: relatively-greatibecause ofthe large Widthr of such grates: There-fre,;the; grateor 19 fUIHBCQUI both, must be so-constructedas-to provide forthisexpansion' without-tleavi-ng-"opene ings through 1 the 1 grate. or:betweenithegrate;- andthe'furnace Wall through whichfuel: can escapewhen the grate is not'fullwexpandedi Various meansihave been suggestedforsthispurpose, but they have generally been unsatisfactory; or'ex:pensive and difficult to construct and to reach forrepairs. i 7

It is among the objects-of this inventionato: provide a-grate the widthof which=rernainssubstantially constant whether. the grate is hot orcold, and through which-fuel can not -fallq A151 other object isto-provide an expansib grate; in which the grate bars remain uniformly.spaced;- apart laterally under allltemperature.conditions.

Further objects are to providesuch agratewhicli is. relatively. simpleand inexpensive to. construct: strong; dependable, very. unlikelyto get;out of order, and has means for maintaining" brazen 3Ov grate bars in"place. I I

In accordance 'withthis invention thereis pro: vided a grate including asupport ifiith "a" "131' I; rality of grate bar supports extendingtransverse ly thereof. A plurality ofgratabars i's"mounted. sideby. sidein rows on" the grate bar'supports; and means is connected to alternatebars in eacli row for spacingthe intermediatebarsuniform distancestherefrom; Theinterrnediate bar'sarei loosely mountedontheg-ratebansupportfs: 40 the spacing means and the portionsaof the itermediate bars which-engage-the spacing"me'a'nsare formed for elevatingthe intermediate-bars when i the bars expandtowardone "anethry When thebars contract; th'eelevated bars are' permittedto drop back to theiroriginal posi f tions andfthe spacing means agai-nmaintai-fi all oftthebars equal distances-*apartL The bars a'r'e also provided .with meansfor interlocking them in; such manner that broken bars? are maintainedin place until removed; v v

1 The'preferred embodiment of the invention 'is illustrated in theaccompanying? drawings inc which Fig.1 ,is-afragmentarvplanzviewlofinaria unexpandedendless chain @grate showmpartly iin 55:;section and with some of the grate bars:remcued':-\;

pins 'l giiboth strands -of each=chaiinbeingn1cori Figs. 2 and.3 areviewsitalien on their-regular Iines II'-II and-IIIIIL respectivelyof-Fig-2 1; Fig; s a plamvievfi of one type of grate bar usediw-i-tlithegrate'; Fig; 5' isa side view thereof; Fig-6 is a -plan view of asecond type of grate 1581 Used: With-*the grate; Fig. 7 is'a'lside newtliereof'eFiglt is a rear VieW,- partly ini's'e'c'tion; of threegrat'ebars in the positions they occupy whert'thegrate'iscold; and-Fig.- 9 isa"viw, -siif1-' ilar to Fig; 8;: showing. the grate bars in the p05sition s they -occupywhen they: have expanses;

Referring: to the'drawin'gs, a traveling chain V grate isishown as beingformed-of wa general parts=,l'-amend1esslchain or belt I" and fuel-supportinggrate bars mounted thereon. The pre ferred' construction 'of thisbelt is best illustrated in Figl lwhere the belt is shoWri-ascofnprisinga; plurality of parallelichain's*3 retainedin spaced relation by meansofcylindrical spacing menubersfll rand -grate bar supports 5. The chainsare preferablya -of the double strandtype' adapted to tiravelmover:sprockets- (not? shown) at the: ends ofua l furnace and formed from' aplurality of links fi pivotallyiconnected at their ends by pivot nectedby the same pins to bring their c'orre-'- spending piv'ot axes intoalignment; A"plurality ohthe spacing .members 4* and grate 'bar supports 5 ."servex-to retain the chains and" their strands of links in:predetermined -spaced parallelrelatiom; thereby" completing: the 'belt;

5' The cylindrical spacing members d aredisposed between the strands ofeach chain with the "pivot pins J= extending; .therethroughp and the"grate bartsupports"5.;have -tubularend portions: l l into which therendsr of pivot 1 pins in adjacentchain's projectw One sideof: the body!portion between the {tubular ends-of:- eachgrate bai support is open,131$ at I 2;- :t'o give access to the pivot'pins projecting intoitso-that they maybe readily drivewout-or 1 replaced should the belt"require repairingaand also to eliminate unnecessary weighti-R- i i Asshown' 'in Fig. 2, each of: the grate barsup ports =is-;provided with anintegral radia'l ribi I 3* projectin gs outwardly from the belt andhavir'ig oppositely disposed side flanges l4 extending-w therefromieThe? rib and flanges project-w across" the pivoted-ends of theadjoiningelinks to within arshortadistance 'of the other 'grate barsupports in 1 line therewith and thereby form transverse"parallelrowsowithi each row taking-' the form of a--rsub'stantial lycontinuous grate bar" supportw The-'tubularend portions" I I ofthegrateubar' s'up portsaare:proividedtwith radial bores "l fi regi's'tr bythe arrows in Figs. 1 and 2. The front end,

of each link 6 is provided with a pair of upwardly tapered lugs 2|forming between them a V-Shaped recess 22, as shown in Fig. 2. Theportions of the grate bar supports which project across the links areformed for engaging the lugs in recesses 22, whereby the grate barsupports are rigidly positioned with relation to the row of links whoselugs 2| they engage. A plurality of fuel-supporting grate bars 2a and 2bis slidably mounted on each row of grate bar supports, the lower portionof each bar being provided with a recess 23 (Figs. 2 and 5) forreceiving radial'rib l3 and its flanges I4, and with inwardly projectinglugs 24 for engaging the under surface of the flanges to retain thegrate bar on its support. The grate bars are prevented from sliding ofithe ends of their supports by end bars 26 (Figs. 2 and 3) that areslidably mounted on the grate bar supports in the same manner as theother bars. Bars 26 are held in place by plates 21 which engage theirouter sides and are detachably connected to belt I by means of nuts 28threaded on pins 29 whose'inner endsare threaded in openings in the endsof adjoining pivot, pins and in ribs l3 of adjoining grate bar supports,the outer ends of pins 29 projecting through plates 21. Thefuel-engaging surfaces of the outermost grate bars 26 are wider than thefuel-engaging surfaces of the other bars, and the bars 26 projectlaterally from the belt be-' yond the grate elements below them andtravel in' close proximity 'to the furnace walls, not shown. a r v Theouter surface of each grate bar is preferably of the form shown in Fig.2 with the outer surface of its nose 3| formed as an arcuate por-,

tion of an imaginary cylindrical surface coaxial with the pivotpinssupporting the grate bar sup-' port oriwhich the'bar is mounted, so thatwhen thegrate rounds the curved endsof its path in a" furnace therows ofgrate bars do not spread apart and open up the fuel-supporting surface.The noses of the grate bars are also preferably narrowed in width toform ash-receiving recesses 32 between them for receiving'ash at one endof the grate and discharging it at the opposite end.

It is a feature of this invention that the grate is so'constructed thatits parts can fully expand and contract with temperature changes withoutchanging in overall width to any appreciable extent and' without'formingopenings through its fuel-supportingsurface through which fuel can fall;Accordingly, the diameters of the bores l6 and I1: through .the gratebar supports and the pivot pins are somewhat greater than the diameterof the bolts disposed therein, and the length of the supportsis lessthan the distance between the sprocket-positioned chains 3 when thegrate isxcold. Consequently, when the grate becomes heated and themembers constituting the beltexpand. transversely thereof, the grate barsupports and the pivot pins are'permitted to telescope relative to eachother, whereby, although the constit-- uen't members of the belt expand,the overall width of the belt is not noticeably increased.

As the grate bars also expand with the heat, it is necessary to makeprovision for such expansion. A former way of doing this was to put afewer number of bars in each row than the row would accommodate and tothen spread out the bars to provide substantially uniform spaces betweenthem into which they could expand. However, it is obvious that as therewas nothing to maintain this uniform spacing of grate bars the vibrationof the moving grate caused them to work together in groups or towardsone side of the grate, thereby leaving relatively large open spaces inthe fuel-supporting surface of the grate through which fuel could fall.

Applicant has eliminated this difficulty by providing some of the gratebars in each row, preferably alternate bars 2a, with laterallyprojecting lugs 33 (Figs. 4, 5 and 8) which engage the sides ofadjoining or intermediate grate bars 2b and space them therefrom, all ofsuch spacing being uniform. Either the surfaces 34 of intermediate bars2b that engage lugs 33 or the lugs upper surfaces which engage theintermediate bars, preferably both as shown in Figs. 8 and 9, areinclined upwardly toward the adjoining bars 2a. The grate bars areslidably mounted on their supports, and recesses 23 are large enough toprovide sufiicient play between the bars and sup ports to permit bars 2bto move outwardly relative to the supports within predetermined limits,

When the bars in any given row'become heated and expand laterally thereis a tendency for the inclined surfaces 34 of intermediate bars 2b andthe inclined upper surfaces of lugs 33 to move toward each other in aplane parallel to belt I, but movement in such a plane is impossiblebe-- cause these surfaces are already in engagementwith each other.Consequently, intermediate bars; 2b ride up the inclined surfaces oflugs, 33; as the bars approach one another, the loose play be. tweenbars 2b and their supports permitting their elevation in this manner.Thus, although the grate bars are originally spaced apart by positivemeans (lugs 33), such means do not prevent the spaces between the barsfrom being closed up when the bars expand, as shown in Fig. 9, wherebylateral expansion of the grate bars is permitted without increase in thelength of the rows of bars.

When the grate cools, the surfaces of the grate bars in effect move awayfrom each other and, as any given alternate bars 2a contract, the inoveragainst an adjacent bar 2a and thereby leave a space between itself andthe bar adjacent its posite side which is double the width it would beif the intermediate bar were equally spaced from adjacent bars 2a onboth sides of it, because the force of gravity causes it to slide downlugs 33 to a point midway between the adjacent bars 2a.

End bars 26 are neither provided with elevating lugs nor elevated whenthe remaining grate bars expand, but the end portionsof grate barsupports 5 on which the 'end bars are mounted are recessed slightly toform shoulders 35, 'as shown in Fig. 3, for limiting the distance thatthe end bars can move inwardly away from the sides of the grate.

. supports 15. and tiltingup at theirrear ends, the

rear portions of, those bars are provided with lateral-ly projectinglugs 36 adapted to strike against the lower faces of shoulders 3.1 onbars 2a when bars 2b attempt to tilt or are elevated, by expane sion..Lugs 36 are disposed farther down from the fuel-supporting surface ofa. grate bar than are lugs 3.3 so that they will not interfere with thedesired elevation of bars 219;. Rear lugs 33 on grate each grate bar isprovided with a, laterally projecting lug 38'and the'opposite side isprovided with a lug-receiving socket 39, these lugs and socketsregistering throughout the length of each row. Thus, the front portionof a broken grate bar is supported by the lug 38 which projects into thesocket 39 of the broken bar. As soon as a broken grate bar is discoveredit can be removed by sliding the bars off one end of their support andsliding on a new bar. Sockets 39 are of such depth and breadth relativeto the length and breadth of lugs 38 as not to interfere with theexpansion of the grate bars and the raising of bars 2b.

A furnace grate constructed in accordance with this invention can beplaced in any furnace without having to construct the furnace to allowfor expansion of the grate. The grate takes care of its own expansion sothat it does not increase in width a noticeable amount. The grate barsforming the surface of such an expansible grate remain uniformly spacedapart laterally so. that openingsare not formed in the fuel-supportingsurface through which fuel could fall and jam the grate or be wasted.The expansion compensating means are simple and'inexpensive andpractically certain not to get out of order. Furthermore, in case agrate bar breaks in this grate the broken pieces are held in place untildiscovered and removed. v

According to the provisions of the patent statutes, I have explained theprinciple and mode of operation of my invention, and have illustratedand described what I now consider to represent its best embodiment.However, I desire to have it understood that, within the scope of theappended claims, the invention may be practiced otherwise than asspecifically illustrated and described.

I claim:

1. A grate comprising a support, a plurality of grate bar supportsconnected thereto, and a plurality of grate bars mounted side by side ina row on each grate bar support, alternate bars in each row beingprovided with means engaging and spacing the intermediate barstherefrom, the intermediate bars being loosely mounted for free verticalmovement on each grate bar support, and said means and the portions ofsaid intermediate bars engaging said means being formed for elevatingthe intermediate bars when the bars expand toward one another, wherebysaid spacing means do not interfere with lateral expansion of the gratebars.

2.. A, grate comprising a support, a plurality of grate bar, supportsconnected thereto, and a plurality of grate bars mounted side by side ina row on each grate bar support, alternate bars in each row beingprovided with means engaging and spacing the intermediate barstherefrom, the intermediate bars being loosely mounted for free verticalmovement on each grate bar support, the engaging surfaces of said meansand the. portions of said intermediate bars engaging said means beinginclined for elevating the inter mediate bars. when the bars expandlaterally toward one another.

3. A grate comprising a support, a plurality of. gratebar. supportsconnected thereto, and a plurality of grate bars mounted side by side ina row on each grate bar support, alternate bars in 'each row beingprovided with means engaging and spacing the intermediate barstherefrom, said intermediate barsbeing provided with shouldersprojecting laterally therefrom, said bar-spacing means projecting belowsaid shoulders on the sides of the intermediate bars, the latter beingloosely mounted for free vertical movement on each grate bar support,and the shoulder-engaging surfaces of said means being inclineddownwardly and outwardly, whereby the intermediate bars are elevated bysaid means when the grate bars expand laterally.

4. A grate comprising a support, a plurality of grate bar supportsconnected thereto, and 'a plurality of grate bars mounted side, by sidein a row on each grate bar support, alternate bars in each row beingprovided with means engaging and spacingthe intermediate bars therefrom,said intermediate bars being provided with shoulders projectinglaterally therefrom, said bar-spacing means projecting below saidshoulders on the sides of the intermediate bars, the latter beingloosely mountedfor free vertical movement on of and supported thereby, aplurality of grate bars mounted side by side in rows on the grate barsupports, and lugs projecting laterally from the sides of alternate barsin each row and engaging the intermediate bars for spacing all of thebars substantially equal distances apart, the intermediate bars beingloosely mounted on the grate bar supports for free vertical movementthereon, the lugs and the portions of said intermediate bars engagingthe lugs being formed for elevating the intermediate bars when the barsexpand laterally toward one another.

6. A grate comprising a support, a plurality of grate bar supportsextending transversely thereof and supported thereby, a plurality ofgrate bars mounted side by side in rows on the grate bar supports, andlugs projecting laterally from the sides of alternate bars in each rowand engaging the intermediatebars for spacing all of the barssubstantially equal distances apart, the intermediate bars being looselymounted on the grate bar supports, the engaging surfaces of the lugs andthe portions of the intermediate bars engaging the lugs being inclinedfor elevating the intermediate bars when the bars expand laterallytoward one another.

7. A grate comprising a support, a plurality of grate bar supportsextending transversely thereof and supported thereby, a plurality ofgrate gaging the intermediate bars for spacing all of the barssubstantially equal distances apart, the intermediate bars being looselymounted on the grate bar supports, the portions of the intermediate-bars engaging the lugs being formed as shoulders, the shoulder-engagingfaces of the lugs being inclined downwardly and outwardly and thelug-engaging faces of the shoulders being inclined upwardly andoutwardly, whereby the intermediate bars are elevated by the lugs whenthe bars expand laterally toward one another.

8. An endless traveling chain grate comprising a plurality of endlesschains advancing in parallel paths and formed of links pivotallyconnected at their ends by pivot pins aligned in parallel rows, aplurality of grate bar supports provided at their ends with axial boresfor slidably receiving the ends of said pivot pins whereby axialmovements of the grate bar supports and the pivot pins relative to eachother are permitted as the grate expands and contracts with temperaturechanges,

.means for limiting said axial movements, and a plurality of grate barsmounted side by side in rows on the grate bar supports, alternate barsin each row being provide-d with means engaging and spacing theintermediate bars therefrom, the intermediate bars being loosely mountedon the grate bar supports for free vertical movement thereon, and saidmeans and the portions of said intermediate bars engaging said meansbeing formed for elevating the intermediate bars when the. bars expandlaterally toward one another.

- 9. A grate comprising a support, a plurality of grate bar supportsextending transversely thereof andsupported thereby, and a plurality ofgrate bars mounted side by side in rows on the grate bar supports,alternate bars in each row being provided with means engaging andspacing the intermediate bars therefrom, the intermediate bars beingloosely mounted on the grate bar supports 'for free vertical movementthereon, said means and the portions of said intermediate bars engagingsaid means being formedfor elevating the intermediate bars when the barsexpand laterally toward one another, and means connected to the bars forlimiting longitudinal rocking of the intermediate bars on said grate barsupports relative to said alternate bars.

' 10. A grate comprising a support, a plurality of a grate bar supportsextending transversely thereof and supported thereby, a plurality ofgrate bars mounted side by side in rows on the grate bar supports, andlugs projecting laterally from the sides of alternate bars in each rowand engaging the intermediate bars for spacing all of the barssubstantially equal distances apart, the intermediate bars being looselymounted on the grate bar supports, the lugs and the portions of saidintermediate bars engaging the lugs being formed for elevating theintermediate bars when the bars expand laterally toward one another,said alternate bars being provided with side shoulders, and lugs on thesides of the intermediate bars projecting beneath said shoulders,whereby rocking of the intermediate bars on said grate bar supportsrelative to said alternate bars is materially limited.

11. A grateicomprising a support, a plurality of grate bar supportsextending transversely thereof and supported thereby, a plurality ofgratebars mounted on each grate bar support andincluding a plurality ofgrate bars loosely mounted for free vertical movement on said grate barsupport, said loosely mounted bars being adapted to be elevated relativeto the remaining bars on said grate bar support and all of said barsbeing disposed. side by side in rows, and lugs projecting laterally fromthe sides of the grate bars adjacent said loosely mounted bars forengaging and spacing the latter therefrom, the engaging surfaces of saidlugs and the portions of said loosely mounted bars engaging the lugsbeing inclined for elevating said loosely mounted bars when the barsexpand laterally toward one another.

l2.-A grate comprising a support, grate bar supports connected thereto,and a plurality of grate bars mounted on each grate bar support andincluding a plurality of grate bars loosely mounted for free verticalmovement on said grate bar support, said loosely mounted bars beingadapted to be elevated relative to the remaining bars on said grate barsupport and all of said bars being disposed side by side in rows, thegrate bars adjacent said loosely mounted bars being provided with meansforengaging and spacing the latter bars therefrom, and said means andthe portions of said loosely mounted bars engaging said means beingformed for elevating the loosely mounted bars when the bars expandtoward one another, whereby said spacing means do not interfere withlateral expansion of the grate bars.

HARRIS B. HOLT.

